Refugium Size Calculator
Enter the display tank volume, how heavily it is stocked and the water depth in the sump. The calculator suggests the refugium volume, the flow through it and a chamber footprint to plan in the sump.
- Refugium volume
- Flow rate
- Chamber size
Water depth is how deep the water stands in the refugium chamber.
A refugium of 10 to 20% of the display suits most tanks. For a 75 gallon reef with an average fish load, about 15% is 11 gallons. Run about 34 to 56 gallons an hour through it, slow enough for macroalgae and pods. Bigger is always better.
Refugium size chart
15% of display. Search for a tank.
| Display (gal) | Refugium (gal) | Range (gal) | Flow (gph) |
|---|---|---|---|
| 20 | 3 | 2.0 to 4.0 | 9 to 15 |
| 40 | 6 | 4.0 to 8.0 | 18 to 30 |
| 55 | 8.2 | 5.5 to 11.0 | 25 to 41 |
| 75 | 11.2 | 7.5 to 15.0 | 34 to 56 |
| 90 | 13.5 | 9.0 to 18.0 | 40 to 68 |
| 125 | 18.8 | 12.5 to 25.0 | 56 to 94 |
| 180 | 27 | 18.0 to 36.0 | 81 to 135 |
| 250 | 37.5 | 25.0 to 50.0 | 112 to 188 |
| 300 | 45 | 30.0 to 60.0 | 135 to 225 |
Gallons.
Tank and refugium
Average fish load. Slide the display volume.
The sump shows the refugium chamber.
How to size a refugium
Tank to chamber. Step through it.
Display
Volume.
Light the refugium on the opposite cycle to the display to steady the pH overnight.
Sump, hang-on or in-tank
Refugium types. Compare them.
Below the tank.
On the back.
Inside.
Hang-on refugiums suit tanks without a sump.
Before you build
Refugium checks. Tick each item.
Tick each item as you go.
Keep the macroalgae trimmed so it keeps taking up nutrients.
What you get
Refugium sizing. Each tile explains one result.
Gallons.
10 to 20%.
An hour.
Footprint.
Fish.
Chaetomorpha is a popular macroalgae because it grows fast and does not go sexual.
Frequently Asked Questions
No question matches that search.
How big should a refugium be?
About ten to twenty per cent of the display tank volume.
What flow does a refugium need?
About three to five times its own volume an hour.
Can a refugium be too big?
Not really. Bigger refugiums do more work.
What size refugium for a seventy-five gallon tank?
About eleven gallons at fifteen per cent.
What goes in a refugium?
Macroalgae such as chaeto, live rock rubble and sand for pods.
What light does a refugium need?
A full spectrum light, often run while the display light is off.
Do I need a sump for a refugium?
No. Hang-on and in-tank refugiums also work.
A cleaner reef
Give the refugium the space and flow it needs and it quietly takes up nutrients and grows food for your tank.
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